Number Sequence Calculator

Find patterns, next terms, and formulas for arithmetic, geometric, and other number sequences.

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About the Number Sequence Calculator

This Number Sequence Calculator identifies patterns in a series of numbers and predicts the next terms. Enter a few consecutive values and it returns the sequence type, a general formula, and the terms that follow.

For arithmetic sequences it uses the formula an = a1 + (n − 1)d, and for geometric sequences it applies an = a1 × rn−1. It also computes partial sums, such as Sn = n/2 × (2a1 + (n − 1)d) for arithmetic series. The calculator needs at least two terms to find an arithmetic or geometric rule, but three or four terms give a more reliable match. If your numbers alternate or grow irregularly, check whether two interleaved patterns fit before trusting a single formula.

  • Enter the known terms of your sequence in order, separated by commas.
  • Select arithmetic or geometric, or let the calculator detect the pattern.
  • Read the identified rule, the general formula, and the next terms in the results.